Composite elastic core yarn

ABSTRACT

A composite yarn formed of an elastic yarn and a false twisted yarn, twisted together in dynamic balance with a controlled predetermined stretch.

United States Patent Gibson et al.

COMPOSITE ELASTIC CORE YARN inventors: Kirkland H. Gibson, Pojac Point, North Kingstown, R.l. 02852; Henry E. Protzmann, 941 Carrs Pond Road, East Greenwich, R.l. 02818 Filed: Dec. 8, 1969 App1.No.: 883,162

Related [1.8. Application Data Continuation-impart of Ser. No. 673,133, Oct. 5, 1967.

U.S.Cl ..57/152,57/140 BY,57/l63 Int. Cl..; 1 ..D02g 3/32 Field of Search ..57/152, 167,12, 140 BY 51 Apr. 25, 1972 References Cited UNITED STATES PATENTS Primary Examiner-John Petrakes Attorney-Barlow & Barlow [57] ABSTRACT A composite yarn formed of an elastic yarn and a false twisted yarn, twisted together in dynamic balance with a controlled predetermined stretch.

6 Claims, 6 Drawing Figures PATENTEDAFR 25 m2 3, 657, 8 73 INVENTORS KIRKLAND H. GIBSON HENRY E. PROTZMANN ATTORNEYS COMPOSITE ELASTIC CORE YARN CROSS REFERENCE This application is a continuation-in-part of our application, Ser. No. 673,l33,filed Oct. 5, 1967.

BACKGROUND OF THE INVENTION A composite yarn formed of elastic yarns and non-elastic yarns has usually been assembled by winding the non-elastic yarns about the elastic yarns while in stretched condition by a circular passing of the non-elastic yarns about the elastic yarns so that the ends of the non-elastic yarns are passed about the elastic yarns. This is relatively is at operation.

The problems of combining an end of an elastic yarn such as spandex* (*Spandex is a generic term, like nylon or rayon, approved by the Federal Trade Commission. Spandex is a manufactured fiber in which the fiber-forming substance is a long chain synthetic polymer comprised of at least 85 percent of a segmented polyurethane.) and an end of stretch nylon are quite different than those encountered when combining two yarns of similar nature. Suggestions as to balancing only the cover have been made as in the Storti US. Pat. No. 3,234,725, but here the elastic core will have a twist imparted thereto by the twister frame which is undesirable.

In the case of false twisted nylon, we have a yarn which can be extended to the normal extension level of the raw nylon from which it was made. Although it normally contains a total of 0.5 turns per inch left or Z (producer twist), it has a strong tendency to twist in the direction in which it was heat set during the false twisting operation. The torque forces will vary depending on the denier, the denier per filament, and the degree of twist imparted which is normally higher as the denier becomes finer. Although the yarn has a definite limit of extension under normal tension, it is almost impossible to determine the limit to which it will contract with no tension applied. The normal stress strain curve of such a yarn starts off very high and levels out in almost straight line relation as tension is applied.

Spandex yarns, whether multi-fil or mono-fil, have a very definite relaxed starting point, and the stress strain curve is almost directly opposite that of the stretch nylon.

SUMMARY OF THE INVENTION The composite yarn here referred to is formed by utilizing an elastic yarn and one or more false twisted non-elastic yarns which, because of their high torque, contract in a kinky fashion. The high torque non-elastic yarns are tensioned to remove the tendency to kink and the elastic yarn is tensioned to a predetermined amount depending upon the stretch in the composite yarn which is desired. Then both yarns are packaged by rotation in a direction to decrease the torque of the false twist non-elastic yarns and to cause these yarns to wrap about the elastic yarn. The twisting of both yarns by packaging is such as to place the composite yarns in dynamic balance.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 diagrammatically illustrates two packages of nonelastic yarn and one package of elastic yarn which are brought together and assembled on a bobbin;

FIG. 2 is a detail elevation showing the tensioning means for the non-elastic yarn;

FIG. 3 is a view of an elevation showing a tensioning means for the elastic yarn;

FIG. 4 is a sectional view showing the tension for the elastic yarn; and

FIG. 5 and FIG. 6 are elevations illustrating the non-elastic yarn as wrapped about the elastic yarn, FIG. 5 being in stretched condition and FIG. 6 in relaxed condition.

DESCRIPTION OF THE PREFERRED EMBODIMENT In order to successfully combine two sets of yarns which are referred to above as spandex and stretch nylon in a twist configuration, it is necessary to employ a precise means of control on both ends to come up with a yarn of predictable characteristics. As a practical matter we introduce enough tension to the nylon end to fully draw out all the crimp,thus establishing the final extensibility of the finished yarn. In the case of the spandex end, we use a compensating tension device which allows us to extend this spandex to a pre-determined value which allows us to establish a predictable contractual force and a predictable limit of contraction for the combination yarn. The degree of extension is determined from a stress strain chart reading in gram level per percentage of elongation.

We have found that by elongating the spandex by means of a compensating tension device, we overcome the variations encountered in the normal method of surface driving the spandex package which does not compensate for inside to outside variations inherent in packaging, traverse motion which is a repetitive error in most spandex packages, and plucks or underwinds which are also very frequently encountered in spandex packages. We are also careful to employ moving guides at all points of the yarn path of the spandex yarn.

The degree and direction of twist added after the front roll is all important. This is of vital importance when you realize that with the spandex end we are dealing with a zero twist yarn and all twist added tends to develop a torque in the opposite direction of the twist, whereas in the nylon end, which already contains a high degree of torque, we must remove torque to a degree equal to the torque being added to the spandex. It can, therefore, be readily seen that the production of a thoroughly torque free finished yarn depends on many factors, and that a precise knowledge and control of the contributing factors must first be established.

Finally, it must be borne in mind that the proper controls must be utilized by the consumer of this yarn in order to realize the maximum benefits for a given end use in subsequent processing and finishing.

With reference to the drawings and particularly FIG. 1, a supporting frame 10 mounts two packages 11 and 12 of nonelastic yarn which has a high false twist therein, something in the order of from 75 to I00 turns per inch. The yarn is a thermoplastic yarn such as a polyester or nylon. The high twist is set in the yarn by heating the same. A package of elastic yarn 15 is also mounted upon the support 10 and is rubber or a substitute rubber, which is known in the trade as spandex. This elastic yarn has no twist. These yarns are led from their supply packages through tension devices and which may be of various characters to a pair of rotating rolls 1? and 18 which nip the elastic yarn 20 and also nip the one or more non-elastic high twisted yarns 21. The yarns 21 are drawn from the packages 11 and 12 possibly over guides 22 and 23, thence through a tension device 24 to the rolls l7 and 18. The elastic yarn 20 is drawn from the package 15 through tension device 16 to the rolls 17, 18. A nip of the elastic yarn 20' and the one or more non-elastic highly twisted yarns 21 occurs at rolls 17, 18, and at this location the non-elastic yarn twists about the elastic yarn. The composite yarn 25 then passes through a guide 26 and is packaged on bobbin 27 by being passed therearound by means of a ring and ring traveler device 28 to form the package 29 The arrow 30 in FIG. 1 indicates the direction which the non-elastic yarns tend to rotate due to their torque, and the arrow 31 indicates the direction of rotation of the bobbin 27. These rotative arrows are in the same direction.

The tension at 24 is such as to remove kinking which occurs by contraction of the high twist in the non-elastic yarns as it is drawn by the nip of the rolls 17 and 18. The tension 16 on elastic yarn is such as to provide in the elastic yarn the amount of contraction desired in the composite yarn and may be measured in a certain number of grams depending upon the contraction which is desired, and while any tension may be used to control this yarn, that here shown will be further described in greater detail.

A twist of the non-elastic yarns about the elastic yarn occurs at substantially the point of nip of the rolls 17 and 18, and the rotation of the bobbin 27 is such that it rotates in the same direction as the non-elastic yarns tend to rotate due to their torque, the rotation being such as to dynamically balance the twist of one yarn on the other. It is found that the non-elastic yarns will wrap about the elastic yarn and form a good cover thereon. One or more non-elastic yarns may be handled in this manner, and where more than one are provided, a better rounding of the covering occurs. The wrapping of the pair of non-elastic yarns 21 about the elastic yarn 20 where this elastic'yarn is in stretched condition is shown in FIG. but which, upon contraction as shown in FIG. 6, provides a complete covering for the elastic yarn.

The tension device for the non-elastic yarns as shown in FIG. 2 is essentially a pair of discs 32 which are urged together by springs 33 which may be tensioned by nuts 34 on the screw shaft 35 held in any desired support 36 by nuts 37 and 38 which enable adjustment or positioning on the shaft.

The tension device 16 comprises a grooved pulley 40 having an O-ring 41 therein to hold the elastic yarn 20 rather securely about the pulley. The pulley is otherwise free to rotate but is also provided with a groove 42 for the reception of a wedgeshaped brake shoe 43 carried by an arm 44 which tends to swing about a pivot axis 45 to urge the wedge into the groove 42. The spring 50 is secured to the arm 44 at 49 tending to swing the arm 44 upward or counterclockwise as seen in FIG. 3. The elastic yarn 20 is led through an eye 46 in the support 47 around the pulley 40 and thence over the pulley 48 at the end of the arm 44 and then downwardly, and as the tension in this elastic yarn increases, it will swing the arm 44 downwardly to release the shoe 43 from the braking groove 42. A spring 50 allowing more yarn to be drawn from package also urges the plate 51 against the arm 44 to provide friction thereon which may be adjusted by a disc 52 on a threaded shaft 45. This disc is non-rotatably and slidably secured to the drum 54 to move to the right in FIG. 3 when the drum 54 is rotated on shaft 45. The drum has teeth 55 on its outer surface and is held in adjusted position by the ratchet pawl 56, spring tensioned from the support 47 and which is released through finger opening 56 in the supporting wall 57,

An example is as follows:

The non-elastic nylon yarn is 70 denier 34 filament (70/34/ l) having a false twist 75 turns per inch lefthand heated (7SZ).

The elastic or spandex yarn is 40 denier tensioned at 16 grams.

The turns of the bobbin assembling the composite yarn is 6,500 R.P.M.

Each end and the composite yarn have 6 turns per inch lefthand twist (6TPIZ).

Note:

Z left-hand twist S right-hand twist The completed product produced by the method described above will consist of a substantial torque free composite structure in which a slight right-hand twist is left in the composite structure for ease in handling. The composite yarn consisting of the two sets of yarn, one elastomeric and the other thermoplastic stretch, is balanced, and it will be appreciated that the maximum elongation will be limited by the false twist stretch yarn as mentioned above. It will also be understood that the false twisted yarn can be either a mono-filament or a multi-filament false twisted yarn, either of which may be drawn from a package.

We claim:

1. The method of providing a torque free composite yarn which comprises drawing from a package a false twisted yarn having a torque in one direction, tensioning said false twisted yarn to remove contractive kinking due to torque, drawing from a second package an untwisted elastic yarn, tensioning said elastic yarn to a predetermined amount dependent upon the stretch desired in the composite yarn, passing said yarns through the nip of a pair of rotating rolls to draw the said yarns from said packages, twisting the false twisted yarn with the elastic yarn at substantially the point of nip by packaging the composite twisted yarns on a bobbin which rotates the composite yarns about the bobbin in the said one direction of rotation that the false twisted torque yarn tends to rotate whereby the torque force of the twist imparted to the elastic yarn is opposite the torque force of the false twisted yarn on the bobbin.

2. The method of claim 1 wherein there are a plurality of false twisted yarns assembled with the elastic yarn, each false twisted yarn having a torque in the said one direction.

3. The method of claim 1 wherein the false twisted yarn is thermoplastic.

4. The method of claim 1 wherein the false twisted yarn is thermoplastic and has had its twist set therein by heating.

5. A torque free composite yarn comprising two sets of yarns twisted together, each of said sets having at least one yarn therein, the first of said sets comprising an elastomeric yarn having a torque force in one direction and the second of said sets comprising a thermoplastic torque stretch yarn having a torque force in the other direction, the torque of each set being substantially equal and opposite.

6. A torque free composite yarn as in claim 5 wherein the second of said sets comprises a plurality of thermoplastic torque stretch yarns, each having a torque force in said other direction, the torque of each set being substantially equal and opposite, wherein the maximum extended length of the composite yarn is equal to the extended length of the thermoplastic yarn. 

1. The method of providing a torque free composite yarn which comprises drawing from a package a false twisted yarn having a torque in one direction, tensioning said false twisted yarn to remove contractive kinking due to torque, drawing from a second package an untwisted elastic yarn, tensioning said elastic yarn to a predetermined amount dependent upon the stretch desired in the composite yarn, passing said yarns through the nip of a pair of rotating rolls to draw the said yarns from said packages, twisting the false twisted yarn with the elastic yarn at substantially the point of nip by packaging the composite twisted yarns on a bobbin which rotates the composite yarns about the bobbin in the said one direction of rotation that the false twisted torque yarn tends to rotate whereby the torque force of the twist imparted to the elastic yarn is opposite the torque force of the false twisted yarn on the bobbin.
 2. The method of claim 1 wherein there are a plurality of false twisted yarns assembled with the elastic yarn, each false twisted yarn having a torque in the said one direction.
 3. The method of claim 1 wherein the false twisted yarn is thermoplastic.
 4. The method of claim 1 wherein the false twisted yarn is thermoplastic and has had its twist set therein by heating.
 5. A torque free composite yarn comprising two sets of yarns twisted together, each of said sets having at least one yarn therein, the first of said sets comprising an elastomeric yarn having a torque force in one direction and the second of said sets comprising a thermoplastic torque stretch yarn having a torque force in the other direction, the torque of each set being substantially equal and opposite.
 6. A torque free composite yarn as in claim 5 wherein the second of said sets comprises a plurality of thermoplastic torque stretch yarns, each having a torque force in said other direction, the torque of each set being substantially equal and opposite, wherein the maximum extended length of the composite yarn is equal to the extended length of the thermoplastic yarn. 